Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands
Autor(a) principal: | |
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Data de Publicação: | 2001 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | https://hdl.handle.net/10216/82092 |
Resumo: | The accessibility of the +3 oxidation state for nickel(II) complexes with N3O2 pentadentate Schiff base ligands prepared by condensation of naphthaldehyde or 3,5- dichlorosalicylaldehyde with triamines (Scheme 1) has been assessed in several solvents, by combining cyclic voltammetry and EPR spectroscopy of the oxidised metal complexes. The data show that trien/Metrien-based ligands act in pentadentate fashion and allow for the stabilisation of electrochemically and chemically generated nickel(III) complexes in all solvents used. The complexes, formulated as [(NiL)-L-III(solv)](+), are low-spin and have a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a greater than or equal to b. For dien-based ligands, steric constraints prevent coordination of the amine nitrogen atom of the pentadentate ligand to the metal centre, thus enforcing a fourfold coordination on the ligand. The resulting complexes can be oxidised to nickel(III) species, but only when using iodine as oxidant, in DMF or (CH3)(2)SO. The complexes are formulated as [(NiL)-L-III(solv)(2)](+), and are low-spin and have a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a much greater than b. The binding of pyridine and cyanide ion to Ni-III trien/Metrien-base complexes was studied by EPR, The data obtained show that these polydentate ligands provide a flexible coordination sphere, and that by varying the ratio equatorial/axial ligand field it is possible to obtain Ni-III in three different ground states. For pyridine adducts, the same ground state as the parent complex was observed with Metrien-based ligands, while for trien-based ligands an inverted ground state ((2)A(1), [a d(epsilon)(2) + b d(x)(2)-(2)(y)], with a much less than b) was observed, as the latter provides a higher axial ligand field. On the other hand, coordination of cyanide adducts induces a change in the principal molecular axis of the Ni-III complexes, in which the cyanide ions occupy equatorial positions, and in which a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a much greater than b, is observed. |
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Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligandsQuímicaChemical sciencesThe accessibility of the +3 oxidation state for nickel(II) complexes with N3O2 pentadentate Schiff base ligands prepared by condensation of naphthaldehyde or 3,5- dichlorosalicylaldehyde with triamines (Scheme 1) has been assessed in several solvents, by combining cyclic voltammetry and EPR spectroscopy of the oxidised metal complexes. The data show that trien/Metrien-based ligands act in pentadentate fashion and allow for the stabilisation of electrochemically and chemically generated nickel(III) complexes in all solvents used. The complexes, formulated as [(NiL)-L-III(solv)](+), are low-spin and have a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a greater than or equal to b. For dien-based ligands, steric constraints prevent coordination of the amine nitrogen atom of the pentadentate ligand to the metal centre, thus enforcing a fourfold coordination on the ligand. The resulting complexes can be oxidised to nickel(III) species, but only when using iodine as oxidant, in DMF or (CH3)(2)SO. The complexes are formulated as [(NiL)-L-III(solv)(2)](+), and are low-spin and have a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a much greater than b. The binding of pyridine and cyanide ion to Ni-III trien/Metrien-base complexes was studied by EPR, The data obtained show that these polydentate ligands provide a flexible coordination sphere, and that by varying the ratio equatorial/axial ligand field it is possible to obtain Ni-III in three different ground states. For pyridine adducts, the same ground state as the parent complex was observed with Metrien-based ligands, while for trien-based ligands an inverted ground state ((2)A(1), [a d(epsilon)(2) + b d(x)(2)-(2)(y)], with a much less than b) was observed, as the latter provides a higher axial ligand field. On the other hand, coordination of cyanide adducts induces a change in the principal molecular axis of the Ni-III complexes, in which the cyanide ions occupy equatorial positions, and in which a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a much greater than b, is observed.20012001-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/10216/82092eng1434-194810.1002/1099-0682(200106)2001:6<1483::aid-ejic1483>3.0.co;2-xPinho, DGomes, PFreire, Cde Castro, Binfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-26T15:13:35ZPortal AgregadorONG |
dc.title.none.fl_str_mv |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands |
title |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands |
spellingShingle |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands Pinho, D Química Chemical sciences |
title_short |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands |
title_full |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands |
title_fullStr |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands |
title_full_unstemmed |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands |
title_sort |
Ground state modulation in nickel(III) chemistry by controlling axial ligation in complexes with N3O2 pentadentate ligands |
author |
Pinho, D |
author_facet |
Pinho, D Gomes, P Freire, C de Castro, B |
author_role |
author |
author2 |
Gomes, P Freire, C de Castro, B |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
Pinho, D Gomes, P Freire, C de Castro, B |
dc.subject.por.fl_str_mv |
Química Chemical sciences |
topic |
Química Chemical sciences |
description |
The accessibility of the +3 oxidation state for nickel(II) complexes with N3O2 pentadentate Schiff base ligands prepared by condensation of naphthaldehyde or 3,5- dichlorosalicylaldehyde with triamines (Scheme 1) has been assessed in several solvents, by combining cyclic voltammetry and EPR spectroscopy of the oxidised metal complexes. The data show that trien/Metrien-based ligands act in pentadentate fashion and allow for the stabilisation of electrochemically and chemically generated nickel(III) complexes in all solvents used. The complexes, formulated as [(NiL)-L-III(solv)](+), are low-spin and have a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a greater than or equal to b. For dien-based ligands, steric constraints prevent coordination of the amine nitrogen atom of the pentadentate ligand to the metal centre, thus enforcing a fourfold coordination on the ligand. The resulting complexes can be oxidised to nickel(III) species, but only when using iodine as oxidant, in DMF or (CH3)(2)SO. The complexes are formulated as [(NiL)-L-III(solv)(2)](+), and are low-spin and have a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a much greater than b. The binding of pyridine and cyanide ion to Ni-III trien/Metrien-base complexes was studied by EPR, The data obtained show that these polydentate ligands provide a flexible coordination sphere, and that by varying the ratio equatorial/axial ligand field it is possible to obtain Ni-III in three different ground states. For pyridine adducts, the same ground state as the parent complex was observed with Metrien-based ligands, while for trien-based ligands an inverted ground state ((2)A(1), [a d(epsilon)(2) + b d(x)(2)-(2)(y)], with a much less than b) was observed, as the latter provides a higher axial ligand field. On the other hand, coordination of cyanide adducts induces a change in the principal molecular axis of the Ni-III complexes, in which the cyanide ions occupy equatorial positions, and in which a (2)A(1), [a d(z)(2) + b d(x)(2)-(2)(y)], ground state, with a much greater than b, is observed. |
publishDate |
2001 |
dc.date.none.fl_str_mv |
2001 2001-01-01T00:00:00Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
https://hdl.handle.net/10216/82092 |
url |
https://hdl.handle.net/10216/82092 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
1434-1948 10.1002/1099-0682(200106)2001:6<1483::aid-ejic1483>3.0.co;2-x |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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